Cellular responses in bee venom (BV) allergy is a controversial issue. Previous studies could not reach an agreement whether this mechanism is activated as a result of allergic sensitization to bee venom. All previous works have used lymphocyte proliferation as their method to analyze cell-mediated immunity. In the present work, we tried to explore whether the production of macrophage migration inhibition factor (MIF), which is another in vitro correlate with cellular responses, is increased in these patients. We also examined which of the major antigenic components of BV played a significant role in the cellular response. Peripheral blood lymphocytes from 10 patients with systemic allergic reactions to bee sting and 9 healthy volunteers were examined for their ability to induce positive MIF reponses. Macrophage inhibition was significantly increased in allergic patients when tested with BV, phospholipase A2 (PLA2) and with melittin. Positive MIF responses to other components were also more common in allergic patients than in the control group. Our results indicate that cellular response to BV is expressed in patients with systemic allergic reaction to BV. When major antigenic components of BV are examined, PLA2 seems to play the major role in inducing this response.